In the field of radio communications, communication systems using new communication formats are being constructed and radio services are being provided accompanying advances in technology. At that time, since normally numerous users do not switch to a new radio service immediately, but rather switch gradually, multiple radio services are implemented in parallel. In addition, when constructing new communication formats, although this involves the introduction of new, dedicated equipment to accommodate those formats, since existing services are still being implemented, it is necessary to secure locations for installing the dedicated equipment that is compatible with the new communication format.
FIG. 10 is a drawing depicting an example of the configuration of a radio base station (BTS) 200 of the prior art (see, for example, Non-Patent Document 1). The radio base station 200 is provided with a radio equipment (RE) 220 which performs out processing on radio signals such as filtering, modulation and frequency conversion, and a radio equipment controller (REC) 210 which performs processing on baseband signals. The radio equipment 220 and the radio equipment controller 210 are connected by an optic fiber in the form of an optical communication cable, and an interface in the form of a common public radio interface (CPRI) is interposed there between.
In addition, the following Patent Document 1 indicates an example of the prior art that uses this type of CPRI for the interface.
Non-Patent Document 1: CPRI Specification V2.1
Patent Document 1: PCT Application Publication No. WO/2008/120297